Unit 1: Levels of Organization & Scientific Method

Levels of Organization in Biology

Biological systems are organized in a hierarchical manner, from the smallest units to the largest. Understanding these levels helps explain how life is structured and functions.

• Atom: The basic unit of matter.

• Molecule: Two or more atoms bonded together.

• Macromolecule: Large molecules essential for life, such as proteins, nucleic acids, carbohydrates, and lipids.

• Organelle: Specialized structures within cells (e.g., nucleus, mitochondria).

• Cell: The basic unit of life.

• Tissue: Groups of similar cells performing a specific function.

• Organ: Structures composed of tissues working together (e.g., heart, liver).

• Organ System: Groups of organs that perform related functions (e.g., digestive system).

• Organism: An individual living thing.

• Population: All individuals of a species in an area.

• Community: All populations in a given area.

• Ecosystem: Communities plus their nonliving environment.

• Biosphere: All ecosystems on Earth.

Energy Flow and Nutrient Cycles

Energy flows through ecosystems via food chains and food webs, while nutrients cycle through biogeochemical cycles.

• Producers: Organisms (usually plants) that convert solar energy into chemical energy via photosynthesis.

• Consumers: Organisms that obtain energy by eating other organisms.

• Decomposers: Break down dead matter, recycling nutrients.

• Cycles: Carbon, nitrogen, water, and phosphorus cycles are essential for ecosystem function.

Homeostasis

Homeostasis is the maintenance of stable internal conditions despite changes in the environment.

• Example: Regulation of body temperature in mammals.

Domains of Life

All living organisms are classified into three domains: Bacteria, Archaea, and Eukarya.

• Bacteria: Prokaryotic, unicellular organisms.

• Archaea: Prokaryotic, often found in extreme environments.

• Eukarya: Eukaryotic organisms, including plants, animals, fungi, and protists.

Scientific Method

The scientific method is a systematic approach to investigation.

• Steps:

  1. Observation

  2. Hypothesis

  3. Experiment

  4. Data Collection

  5. Analysis

  6. Conclusion

• Variables:

  • Independent Variable: The factor changed by the experimenter.

  • Dependent Variable: The factor measured in response.

  • Control Group: Group not exposed to the independent variable.

  • Experimental Group: Group exposed to the independent variable.

• Statistical Significance: Indicates whether results are likely due to chance.

Unit 2: Basic Chemistry for Biology

Atoms, Elements, and Isotopes

Atoms are the basic units of matter, composed of protons, neutrons, and electrons.

• Proton: Positively charged particle in the nucleus.

• Neutron: Neutral particle in the nucleus.

• Electron: Negatively charged particle orbiting the nucleus.

• Atomic Number: Number of protons in an atom.

• Isotope: Atoms of the same element with different numbers of neutrons.

Ions and Chemical Bonds

Ions are atoms that have gained or lost electrons, resulting in a charge. Chemical bonds form between atoms to create molecules.

• Ionic Bond: Formed when electrons are transferred from one atom to another.

• Covalent Bond: Formed when atoms share electrons.

• Polar Covalent Bond: Unequal sharing of electrons, leading to partial charges.

• Nonpolar Covalent Bond: Equal sharing of electrons.

• Hydrogen Bond: Weak attraction between a hydrogen atom and another electronegative atom.

Electronegativity

Electronegativity is an atom's ability to attract electrons in a bond. Differences in electronegativity determine bond type.

• Example: Water (H2O) is polar because oxygen is more electronegative than hydrogen.

Water: Properties and Importance

Water is essential for life due to its unique properties.

• Cohesion: Water molecules stick to each other.

• Adhesion: Water molecules stick to other surfaces.

• High Specific Heat: Water resists temperature changes.

• Solvent: Water dissolves many substances.

Acids, Bases, and pH

Acids and bases are substances that affect the concentration of hydrogen ions in a solution.

• Acid: Increases H+ concentration; pH < 7.

• Base: Decreases H+ concentration; pH > 7.

• pH Scale: Measures acidity or alkalinity; ranges from 0 (acidic) to 14 (basic).

• Buffer: Substance that resists changes in pH.

Table: Examples of Acids and Bases

Unit 3: Organic Molecules & Macromolecules

Organic Molecules

Organic molecules contain carbon and are the basis of life. They include carbohydrates, lipids, proteins, and nucleic acids.

• Functional Groups: Specific groups of atoms that confer particular properties (e.g., hydroxyl, carboxyl, amino).

• Hydrocarbon: Molecules made of only carbon and hydrogen.

Macromolecules

Macromolecules are large, complex molecules essential for life.

• Carbohydrates: Provide energy and structural support. Monomers are monosaccharides (e.g., glucose).

• Lipids: Store energy and make up cell membranes. Include fats, oils, and phospholipids.

• Proteins: Made of amino acids; perform many cellular functions.

• Nucleic Acids: Store genetic information (DNA, RNA).

Monomers and Polymers

Macromolecules are formed by joining monomers into polymers.

• Monomer: Small unit that can join with others to form a polymer.

• Polymer: Large molecule made of repeating monomers.

Condensation and Hydrolysis Reactions

Polymers are formed and broken down by specific chemical reactions.

• Condensation (Dehydration Synthesis): Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

Equation for Hydrolysis:

Carbohydrates: Structure and Function

Carbohydrates are classified by the number of sugar units.

• Monosaccharide: Single sugar unit (e.g., glucose, fructose).

• Disaccharide: Two sugar units (e.g., sucrose, lactose).

• Polysaccharide: Many sugar units (e.g., starch, glycogen, cellulose).

Table: Types of Carbohydrates

Lipids: Structure and Function

Lipids are hydrophobic molecules important for energy storage and membrane structure.

• Fatty Acids: Building blocks of lipids; can be saturated or unsaturated.

• Triglyceride: Three fatty acids bonded to glycerol.

• Phospholipid: Major component of cell membranes.

Proteins: Structure and Function

Proteins are polymers of amino acids and perform a wide variety of functions.

• Amino Acid: Monomer of proteins; contains amino and carboxyl groups.

• Peptide Bond: Covalent bond joining amino acids.

• Levels of Structure: Primary, secondary, tertiary, and quaternary.

Nucleic Acids

Nucleic acids store and transmit genetic information.

• DNA: Deoxyribonucleic acid; stores genetic code.

• RNA: Ribonucleic acid; involved in protein synthesis.

Additional info:

• Some content inferred from context and standard biology curriculum (e.g., details on macromolecules, levels of organization, and chemical bonds).

• Tables and equations formatted for clarity and completeness.